DE69409441T2 - Electrophotographic, photosensitive member, process cartridge and electrophotographic apparatus using the same - Google Patents

Description

Field of the invention

The invention relates to an electrophotographic photosensitive member, in particular to an electrophotographic photosensitive member having an intermediate layer containing a resin having a specific structure.

The invention also relates to a process cartridge and an electrophotographic apparatus using the above electrophotographic photosensitive member.

Related prior art

The electrophotographic photosensitive member normally comprises a photosensitive layer on an electrically conductive support. Usually, the photosensitive layer is extremely thin and its thickness tends to be uneven at defective points such as scratches and adhesions on the surface of the support. This tendency toward unevenness is particularly notable in the widely used function-separated type photosensitive layer consisting of a charge-generating layer which is 0.5 µm thin and a charge-transporting layer.

It is necessary that the photosensitive layer be as uniform as possible in thickness, since irregularity in thickness leads to irregularity in potential or sensitivity.

Another important characteristic of the electrophotographic photosensitive member is the stability of the light area potential and the dark area potential during repeated use. Without potential stability, the image density produced will be unstable or the image produced will have fog.

To compensate for such disadvantages, an intermediate layer is provided which serves to cover any surface defect of the support, to improve the adhesion of the support to the photosensitive layer and to prevent charge carrier injection from the support into the photosensitive layer.

The intermediate layer is usually formed of a resin including polyamide resins (Japanese Patent Laid-Open Nos. 48-47344 and 52-25638), polyester resins (Japanese Patent Laid-Open Nos. 52-20836 and 54-26738), polyurethane resins (Japanese Patent Laid-Open Nos. 53-89435 and 2-115858), acrylic polymers containing quaternary ammonium salts (Japanese Patent Laid-Open No. 51-126149) and casein (Japanese Patent Laid-Open No. 55-103556).

However, the intermediate layer formed of any of the above materials changes its electrical resistance depending on the temperature and humidity. Therefore, an excellent electrophotographic photosensitive member having excellent and stable potential characteristics under all environmental conditions from low temperature and low humidity to high temperature and high humidity cannot be obtained.

For example, when the photosensitive member is repeatedly used under the conditions of low temperature and low humidity where the electrical resistance of the intermediate layer tends to increase, the electric charge tends to tends to remain in the intermediate layer, which leads to an increase in the bright area potential and the residual potential. Consequently, the copied images show a fog during normal development or the images become thin during reversal development, which means that a desired quality of the recorded images cannot be achieved in the long term.

On the other hand, there is a tendency that the barrier function of the intermediate layer decreases under the conditions of high temperature and high humidity and the carrier injection from the carrier increases, whereby the potential of the dark area decreases. Consequently, the copied images become thin in the normal development or the images show black dot-like defects or have fog in the reversal development.

In addition, the intermediate layer often causes a decrease in the sensitivity of the photosensitive element, even if the intermediate layer improves the stability of the potential at low temperature and low humidity and prevents the formation of black dot-like defects in the image at high temperature and high humidity.

SUMMARY OF THE INVENTION

The invention intends to provide an electrophotographic photosensitive member which exhibits stable and excellent potential characteristics under all environmental conditions from low temperature and low humidity to high temperature and high humidity and is capable of producing images which are invariably as excellent as at the initial stage.

The invention also intends to provide an electrophotographic photosensitive member comprising an intermediate layer having sufficiently high adhesiveness to the support and excellent film-forming properties, and producing an excellent defect-free image with high sensitivity.

The invention further intends to provide a process cartridge and an electrophotographic apparatus using the above electrophotographic photosensitive member.

The electrophotographic photosensitive member of the invention comprises an electroconductive support, an intermediate layer formed on the electroconductive support, and a photosensitive layer formed on the intermediate layer, the intermediate layer containing a resin having a polyamic acid structure or a polyamic acid ester structure represented by formulas (1) and (2) shown below, with the proviso that the intermediate layer is free of a conductive substance when the resin conforms to formula (1).

The process cartridge and the electrophotographic apparatus of the invention use the above electrophotographic photosensitive member.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 schematically shows the structure of an electrophotographic apparatus using an electrophotographic photosensitive member of the invention.

Fig. 2 shows an example of a block diagram of a facsimile system using the electrophotographic photosensitive member of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The intermediate layer of the electrophotographic photosensitive member of the invention contains a resin having a polycarbamoylcarboxylic acid structure or a polycarbamoylcarboxylic acid ester structure.

The carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure may include various structures, which are given later, and particularly preferred structures are given by formulas (1) and (2)

wherein A₁ is a divalent organic group; R₁ to R₆ are independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a cyano group; R₇ and R₈ are independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyalkyl group or a substituted or unsubstituted aralkyl group, and

wherein A2 is a divalent organic group; R9 to R14 are independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a cyano group; R15 and R16 are independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyalkyl group or a substituted or unsubstituted aralkyl group; and X is an oxygen atom, a substituted or unsubstituted alkylene group, a carbonyl group or a sulfonyl group.

The above divalent organic group, A₁ and A₂, includes various groups as mentioned later.

Particularly preferred are the groups represented by formulas (3) and (4):

- Ar1 - (3)

wherein Ar₁ is a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group; and

-Ar₂-Y-Ar₃- (4)

wherein Ar₂ and Ar₃ are independently a substituted or unsubstituted aromatic hydrocarbon ring group or a substituted or unsubstituted aromatic heterocyclic group; and Y is an oxygen atom, a sulfur atom, a substituted or unsubstituted alkylene group, a carbonyl group or a sulfonyl group.

The aromatic hydrocarbon group for Ar₁, Ar₂ and Ar₃ includes phenylene, biphenylene, naphthalene and the like, and the heterocyclic group for Ar₁, Ar₂ and Ar₃ includes pyridinediyl, thiophenediyl and the like. The alkylene group for Y includes methylene, ethylene, propylene, isopropylene and the like. The substituent with which the above groups may be substituted includes alkyl groups such as methyl, ethyl and propyl; halogen atoms such as fluorine, chlorine and bromine; halomethyl groups such as trifluoromethyl; alkoxy groups such as methoxy, ethoxy and propoxy; alkylamino groups such as dimethylamino and diethylamino; acyl groups such as acetyl and benzoyl, and a cyano group.

Preferred examples of the divalent organic group A₁ and A₂ are shown below, but the groups are by no means limited thereto.

Of these preferred groups, the following are particularly preferred.

Of these, the following are particularly preferred:

In the formulas (1) and (2), R₁ to R₆, and R₉ to R₁₄ independently represent a hydrogen atom, a halogen atom such as fluorine, chlorine and bromine, an alkyl group such as methyl, ethyl and propyl, an alkoxy group such as methoxy, ethoxy and propoxy, and a cyano group. R₁ to R₆, and R₉ to R₁₄ may further have a substituent such as a halogen atom.

In formulas (1) and (2), R₇, R₈, R₁₅ and R₁₆ independently represent a hydrogen atom, an alkyl group such as methyl, ethyl and propyl, an alkoxyalkyl group such as methoxyethyl, and an aralkyl group such as benzyl. R₇, R₈, R₁₅ and R₁₆ may further have a substituent such as a halogen atom.

In the formula (2), X as the alkylene group includes groups of methylene, ethylene, propylene and isopropylene, and the substituent with which the alkylene group may be substituted includes halogen atoms such as fluorine, chlorine and bromine, acyl groups such as acetyl and benzoyl, and a cyano group.

The resin used in the invention preferably has a number average molecular weight of 500 to 100,000, more preferably 10,000 to 50,000.

In the process for producing the electrophotographic photosensitive member of the invention, a polyimide structure may be formed in the polycarbamoylcarboxylic acid structure or the polycarbamoylcarboxylic acid ester structure by a dehydration reaction of the amide group with the acid group or the acid ester group depending on the conditions of the drying treatment usually carried out. In the invention, the segment having the carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure in the resin preferably 20 to 80 mol%, more preferably 40 to 60 mol% of the segments in the entire resin. The reason for this is not clear. Presumably, the poly(carbamoylcarboxylic acid) structure or the poly(carbamoylcarboxylic acid) ester structure hinders injection of positive holes from the electrically conductive carrier to promote dissociation of the charge carriers generated by the charge generating substance and injection of the electrons into the intermediate layer, and the densely packed polyimide structure further promotes the above dissociation of the charge carriers and injection and transfer of electrons and reduces the influence of moisture.

Specific examples of the resin of the invention are shown below, but the invention is not limited thereby.

Among the above compounds are the Example connections no. 1, 2, 3, 4, 10, 11, 12, 26, 27, 28, 34, 35, 36, 49, 50, 51, 52, 58, 59, 60, 74, 75, 76, 82, 83 and 84 are preferred from the viewpoints of environmental stability of the electrophotographic photosensitive member, internal stability of the compounds, ease of synthesis of the compounds and low cost. Among them, particularly preferred are Example Compound Nos. 1, 3, 10, 27, 34, 49, 51, 58, 75 and 82.

The resin having the polycarbamoylcarboxylic acid structure can be synthesized by a ring-opening polyaddition reaction of a tetracarboxylic acid dianhydride and a diamine in an organic polar solvent. The organic polar solvent includes amide type solvents such as N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone, phenol type solvents such as cresol and chlorophenol, ether type solvents such as diethylene glycol dimethyl ether, and mixtures thereof. In order to control the molecular weight of the resin, water may be contained in a content of not more than 5%. The reaction temperature is preferably in a range of 20°C to 120°C, more preferably 20°C to 40°C.

The resin having the polycarbamoylcarboxylic acid ester structure used in the invention can be synthesized by esterifying the above polycarbamoylcarboxylic acid with an alcohol in the presence of an appropriate catalyst. The catalyst includes mineral acids such as sulfuric acid and hydrochloric acid and organic acids such as p-toluenesulfonic acid. The resin can also be synthesized by reacting a half-esterified tetracarboxylic acid diamine with a diamine.

The above-mentioned polyimide can be synthesized by heating the above polycarbamoylcarboxylic acid or polycarbamoylcarboxylic acid ester at a temperature preferably in the range of 50°C to 400°C and for a heat treatment time preferably in the range of 5 minutes to 4 hours. The temperature and time of this heat treatment greatly affect the ratio of the polycarbamoylcarboxylic acid or polycarbamoylcarboxylic acid ester to the polyimide structure. The ratio can be determined by IR spectroscopy from the ratio of the absorbance at 1500 cm-1 assigned to the phenylene to the absorbance at 1770-1780 assigned to the imide or by H1 NMR spectroscopy from the determination of the protons of the carboxylic acid group or the carboxylic acid ester group.

A synthesis example of a polycarbamoylcarboxylic acid used in the invention is shown below.

Synthesis example

In a 500 ml four-necked flask were added 14.7 g (0.05 mol) of the compound represented by the following formula:

and 160 g of N,N-dimethylacetamide under a dry nitrogen gas stream. To this end, 10.0 g of (0.05 mol) of 4,4'-diaminodiphenyl ether. Further, the mixture was allowed to react for 2 hours with stirring in a nitrogen stream to obtain a pale yellow viscous liquid reaction mixture. To the liquid reaction mixture was added 160 g of N,N-dimethylacetamide to obtain a homogeneous solution. The solution was added dropwise to 5 liters of methanol with vigorous stirring. The precipitated polycarbamoylcarboxylic acid was recovered by filtration. The recovered material was again dissolved in 250 g of N,N-dimethylacetamide and the insoluble material was removed by filtration. The filtrate was added dropwise to 5 liters of methanol to precipitate the polymer. The precipitated polymer was washed with 2 liters of methanol and dried to obtain 16.3 g of the polyamide of Example Compound No. 3.

Other polyamides used in the invention can be synthesized in the same manner as above.

The intermediate layer in the invention may have a single layer structure or a two or more layer structure, provided that at least one of the constituent layers contains the resin of the invention. When the intermediate layer is composed of two or more layers, the resins other than those of the invention are exemplified by polyamide resins, polyester resins and phenol resins.

For example, the intermediate layer may consist of a first layer containing the electrically conductive substance and a second layer not containing any electrically conductive substance.

The intermediate layer of the invention may contain a second resin, an additive, an electrically conductive substance or the like, if necessary, in an amount to achieve the effect of the invention. The second resin includes polyamide resins, polyester resins and phenol resins. The additive includes acceptor type compounds such as 2,5,7-trinitrofluorenone and benzoquinone. The electrically Conductive substance includes powdered metals such as aluminum, copper, nickel and silver, short metal fibers, carbon fibers, electrically conductive powdered materials such as carbon black, titanium black, graphite, metal oxides and sulfides (e.g. antimony oxide, indium oxide, tin oxide, titanium oxide, zinc oxide, potassium titanate, barium titanate, magnesium titanate, zinc sulfide, copper sulfide, magnesium oxide, aluminum oxide and the like), and those metal oxides and sulfides whose surface has been treated with an electrically conductive substance, a silane coupling agent or a titanium coupling agent, or which have been subjected to a reduction treatment.

The content of the resin of the invention in the intermediate layer is preferably in the range of 10 to 90% by weight, more preferably 30 to 70% by weight, based on the total weight of the resin-containing intermediate layer.

The thickness of the intermediate layer is suitably determined in consideration of the electrophotographic characteristics and defects of the support, and is preferably in the range of 0.1 to 50 µm, more preferably 0.5 to 30 µm.

The photosensitive layers of the electrophotographic photosensitive members of the invention are roughly classified into a single layer type containing a charge generating substance and a charge transporting substance in one and the same layer, and a lamination type comprising a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. The lamination type is further classified into a type comprising an electrically conductive support, a charge generating layer and a charge transporting layer in the order mentioned, and a type comprising an electrically conductive support, a charge transporting layer and a charge generating layer in the order mentioned. The invention is applicable to the lamination type, particularly to that having a charge generating layer on the charge generating layer. Layer formed charge transport layer.

The charge generating layer can be prepared by dispersing a charge generating substance in a solution of a binder resin in a suitable solvent, applying and drying the solution. The charge generating substance includes azo pigments such as monoazo, bisazo and trisazo, phthalocyanine pigments such as metal phthalocyanines and non-metal phthalocyanines, indigo pigments such as indigo and thioindigo, polycyclic quinone pigments such as anthanthrone and pyrenequinone, perylene pigments such as perylenic anhydride and perylenimide, squarilium dyes, pyrylum and thiapyrylium salts, and triphenylmethane dyes. The binder resin includes vinyl acetal resins, styrene resins, polyester resins, vinyl acetate resins, methacrylic resins, acrylic resins, vinyl pyrrolidone resins and cellulose resins. The thickness of the charge generating layer is preferably not more than 5 µm, more preferably in the range of 0.05 to 2 µm.

The charge transport layer can be prepared by dissolving a charge transport substance mentioned below in a solution of a film-forming resin, and applying and drying the resulting solution. The charge transport substances are classified into electron transport substances and hole transport substances. The electron transport substances include electron withdrawing substances such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil and tetracyanoquinodimethane, and polymers thereof. The hole-transporting substances include polycyclic aromatic compounds such as pyrene and anthracene, heterocyclic compounds such as carbazole, indole, imidazole, oxazole, thiazole, oxadiazole, pyrazole, pyrazoline, thiadiazole and triazole, hydrazone compounds such as p-diethylaminobenzaldehydo-N,N-diphenylhydrazone and N,N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, styryl compounds such as α-phenyl-4-N,N-diaminostilbene and 5-[4-(di-p-tolylamino)benzylidene]-5H-dibenzo[a,djdicycloheptene, Benzidine type compounds, triarylamine type compounds and polymers having a group derived from a triphenylamine compound or an analogous compound in the main chain or the side chain (e.g. poly-N-vinylcarbazole, polyvinylanthracene and the like).

The film-forming resin includes polyester resins, polycarbonate resins, polymethacrylate resins and polystyrene resins.

The thickness of the charge transporting layer is preferably in the range of 5 to 40 µm, more preferably 10 to 30 µm.

When the photosensitive layer is composed of a single layer, it is prepared by applying a solution of a binder resin containing the charge generating substance and charge transporting substance as mentioned above dissolved or dispersed therein onto a substrate and drying it.

The photosensitive layer of the invention may be an organic photosensitive polymer layer of polyvinylcarbazole, polyvinylanthracene or the like, a vapor-deposited layer of the above charge-generating substance, a vapor-deposited layer of selenium, a vapor-deposited layer of selenium-tellurium, an amorphous silicon layer or the like. The photosensitive single layer preferably has a thickness of 5 to 40 µm, more preferably 10 to 30 µm.

The electrically conductive support used in the invention may be made of aluminum, aluminum alloys, copper, zinc, stainless steel, titanium, nickel, indium, gold, platinum or a similar material. The support may also be made of plastic (e.g. polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate and acrylic resins and the like) coated with the above-mentioned metal or alloy by vapor deposition, or it may be a plastic, metal, or an alloy support coated with electrically conductive particles (e.g. carbon black, particulate silver and the like) with a suitable binder, or a plastic or paper sheet impregnated with electrically conductive particles. The support may be in the form of a drum, sheet, belt or the like, and preferably has a suitable shape for the electrophotographic photosensitive member used.

A resin layer serving as a protective layer, which may optionally contain electrically conductive particles, may further be applied to the photosensitive layer in the invention.

The respective above layers can be applied by means of dip coating, spray coating, jet coating, spin coating, roller coating, Meyer bar coating, blade coating or a similar process.

The electrophotographic photosensitive member of the invention is useful for a variety of electrophotographic machines such as electrophotographic copying machines, laser printers, LED printers and liquid crystal shutter type printers, and for machines using electrophotography such as display machines, recording machines, photo-printing machines and engraving machines and facsimile machines.

Fig. 1 schematically shows an example of the structure of a transfer type electrophotographic apparatus using an electrophotographic photosensitive member of the invention.

In Fig. 1, a drum-shaped photosensitive element 1 of the invention is driven and rotates at a predetermined peripheral speed around the axis 1a in the direction of the arrow. The photosensitive element 1 is uniformly charged positively or negatively on the peripheral surface during rotation by means of the electrostatic charging device 2. and then exposed to image exposure light L (e.g., slit exposure, laser beam scanning exposure, and the like) in the exposure region 3 by means of an image exposure device (not shown in the drawing), whereby a latent electrostatic image is successively formed on the peripheral surface in accordance with the exposure image.

The latent electrostatic image formed is developed with a toner by a developing device 4. The developed toner image is successively transferred by a transfer device 5 onto the surface of a transfer-receiving material P which is fed from a transfer-receiving material feed device, not shown in the drawing, to the position between the photosensitive member 1 and the transfer device 5 in synchronism with the rotation of the photosensitive member 1.

The transfer recording material P having received the transferred image is separated from the surface of the photosensitive member and passed to an image fixing device 8 for fixing the image and output as a copy from the copying machine.

The surface of the photosensitive member 1 is cleaned after image transfer by a cleaning device 6 to remove remaining untransferred toner, and is treated for charge elimination by a pre-exposure device 7 for repeated use in image formation.

Two or more of the above constituent elements including the electrophotographic photosensitive member 1, the electrostatic charging device 2, the developing device 4, the cleaning device 6 and the like may be integrated into one body as a process cartridge in the invention. This process cartridge may be designed so that it can be dismounted from the main body. For example, at least one device selected from the charging device 2, the developing device 4 and the cleaning device 6, is combined with the photosensitive member 1 to form a cassette which can be dismounted from the main body by means of a guide device such as a rail in the main body.

When the electrophotographic apparatus is used as a copying machine or as a printer, the optical light L for exposing the image may be projected onto the photosensitive member as light reflected or transmitted from an original, or otherwise the information read out from an original by a sensor may be converted into signals, and light is projected onto the photosensitive member by means of scanning a laser beam, driving an LED array, or driving a liquid crystal shutter array in accordance with the signal.

When the electrophotographic apparatus is used as a printer or a facsimile machine, the optical light L is used to expose an image for printing the received data. Fig. 2 is a block diagram of an example of this case.

A control device 11 controls the image reading part 10 and a printer 19. The entirety of the control device 11 is controlled by a CPU 17. The data read out by the image reading part 10 is transmitted to another communication station by means of a transmission circuit 13. The data received from the other communication station is transmitted to a printer 19 via a receiver circuit 12. The image data is stored in an image memory 16. A printer controller 18 controls the printer 19. The reference numeral 14 denotes a telephone system.

The image received via the circuit 15, i.e. the image information from a remote data station connected via the circuit, is demodulated by the receiver circuit 12 to decode the image information into the CPU 17, and successively stored in the image memory 16. When at least one page of image information has been stored in the image memory 16, the images are recorded in such a manner that the CPU 17 reads out one page of image information and sends the one page of decoded information to the printer controller 18, which controls the printer 19 upon receiving the one page of information from the CPU to record the image information. During recording by the printer 19, the CPU 17 receives the next page of information.

Images are received and recorded in the manner described above.

The invention will be described in more detail with reference to Examples. In the Examples, the term "parts" refers to weight.

example 1

On an aluminum plate, a solution of 5 parts of polycarbamoylcarboxylic acid represented by Example Compound No. 3 in 95 parts of N,N-dimethylacetamide was applied by means of a Meyer rod and dried at 140 °C for 10 minutes to form an intermediate layer having a thickness of 1 µm.

Separately, 5 parts of the azo pigment represented by the following formula:

to 90 parts of tetrahydrofuran and dispersed by a sand mill for 20 hours. To this dispersion was added a solution of 2.5 parts of a butyral resin (BLS, manufactured by Sekisui Chemical Co., Ltd.) in 20 parts of tetrahydrofuran and the mixture was further dispersed for 2 hours. subjected to a dispersion treatment. This dispersion was diluted with 100 parts of cyclohexanone and 100 parts of tetrahydrofuran. This diluted dispersion was applied to the above-mentioned intermediate layer with a Meyer bar and dried to form a charge generating layer having a thickness of 0.2 µm.

Then a solution of 5 parts of triarylamine was added, which is represented by the following formula:

and 5 parts of a polycarbonate resin (Z-2001 manufactured by Mitsubishi Gas Chemical Co., Ltd.) in 40 parts of monochlorobenzene was applied to the charge generating layer prepared above by means of a Meyer bar and dried to form a charge transporting layer having a thickness of 20 µm.

The charging characteristics of the prepared electrophotographic photosensitive member were tested by means of an electrostatic copying machine tester (model: SP-428, manufactured by Kawaguchi Denki K.K.). Using the tester, the electrophotographic photosensitive member was negatively charged by a corona discharge of -5 kV, left in the dark for one second, and exposed to a halogen lamp with an illuminance of 10 lx (lux). The charging characteristics evaluated were the surface potential (V0), the sensitivity (E1/2, the amount of irradiation required for a drop from V0 to 1/2 V0), and the residual potential (Vr, the potential after pre-exposure).

The results are shown in Table 1.

Examples 2 - 10

In the same manner as in Example 1, each electrophotographic photosensitive member was prepared and evaluated except that the polycarbamoylcarboxylic acid of Example Compound No. 3 was replaced with the polycarbamoylcarboxylic acid or polycarbamoylcarboxylic acid ester shown in Table 1. The results are shown in Table 1.

Comparison example 1

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the intermediate layer was formed using a solution of 5 parts of an alcohol-soluble copolymer nylon (Amilan CM-8000, manufactured by Toray Industries, Inc.) in 95 parts of methanol.

The results are shown in Table 1.

Comparison example 2

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the intermediate layer was dried at 100°C for 60 minutes and heat-treated at 250°C for 3 hours. It was found by infrared spectroscopy that the carbamoylcarboxylic acid structure in the resin of the intermediate layer was completely converted to an imide structure. The results are shown in Table 1.

Example 11

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1, except that an aluminum cylinder (outer diameter: 30 mm, length: 360 mm) was used instead of the aluminum plate, the intermediate layer was dried at 140 °C for 30 minutes, the thickness of the intermediate layer was 20 µm, and the respective layers were formed by dip coating.

The obtained electrophotographic photosensitive member was mounted in a normal development type copier for plain paper, which carried out the processes of electrostatic charging, exposure, development, image transfer and cleaning in a cycle of 0.8 second, and the durability was tested for continuous copying of 10,000 sheets at low temperature and low humidity (15 ºC, 15% RH). The evaluation was made by measuring the dark area potential (VD) at the initial stage, the light area potentials (VL) at the initial stage and after the durability test, and by visually observing the copied images.

Separately, the intermediate layer formed in the same manner as above, without subsequent formation of a photosensitive layer, was subjected to a lattice pattern cut peeling test (according to JIS K-5400).

The results are shown in Table 2.

Examples 12 - 20

Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Example 11 except that the coating liquids for forming the intermediate layer in Examples 2 to 10 were used, respectively.

The results are shown in Table 2.

Comparison example 3

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 11 except that the solutions for forming the intermediate layer were the same as those used in Comparative Example 1.

The results are shown in Table 2.

Comparison example 4

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 11 except that the intermediate layer was prepared with a solution of 14 parts of polyester polyol (Nipporane-125, manufactured by Nippon Polyurethane Industry Co., Ltd.), 6 parts of 2,6-toluene diisocyanate, 0.02 part of dibutyltin dilaurate in 80 parts of methyl ethyl ketone.

The results are shown in Table 2.

Comparison example 5

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 11 except that the intermediate layer was formed with the coating liquid for the intermediate layer used in Comparative Example 2.

The results are shown in Table 2.

Example 21

A coating liquid for forming a first intermediate layer was prepared by mixing 25 parts of the polycarbamoylcarboxylic acid of Example Compound No. 3, 50 parts of an electrically conductive powdery titanium oxide coated with tin oxide containing 10% of antimony oxide, and 25 parts of N,N-dimethylacetamide and subjecting it to a dispersion treatment using a sand mill for 20 hours.

This liquid dispersion was applied to an aluminum plate using a Meyer rod and dried at 140 ºC for one hour to obtain the first intermediate layer, which was 13 µm thick.

On the above first intermediate layer, another intermediate layer (second intermediate layer) was formed in the same manner as in the formation of the intermediate layer of Example 1 to have a thickness of 0.5 µm. Further, a charge generating layer was formed thereon in the same manner as in Example 1. layer and a charge-transporting layer are formed.

The obtained electrophotographic photosensitive member was evaluated in the same manner as in Example 1.

The results are shown in Table 3.

Examples 22 - 30

Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Example 21 except that a polycarbamoylcarboxylic acid or a polycarbamoylcarboxylic acid ester shown in Table 3 was used instead of Example Compound No. 3.

The results are shown in Table 3.

Comparison example 6

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 21, except that the first intermediate layer was formed by means of a liquid dispersion composed of 25 parts of resole phenolic resin (Plyophen J-325, manufactured by Dainippon Ink and Chemicals, Inc.), 50 parts of an electroconductive powdery titanium oxide coated with tin oxide containing 10% antimony oxide, 25 parts of methyl cellosolve and 5 parts of methanol and subjected to a dispersion treatment for 20 hours, and the second intermediate layer was formed by means of a solution of 5 parts of an alcohol-soluble copolymer nylon (Amilan CM-8000, manufactured by Toray Industries, Inc.) in 95 parts of methanol.

The results are shown in Table 3.

Examples 31 - 34

Electrophotographic photosensitive members were prepared and evaluated in the same manner as in Examples 21, 24, 26 and 29, except that an aluminum cylinder (outer diameter: 30 mm, length: 360 mm) was used instead of the aluminum plate, and the layers were formed by dip deposition.

The electrophotographic photosensitive members were evaluated in the same manner as in Example 11, without conducting a peeling test by cutting a grid pattern.

The results are shown in Table 4.

Examples 35 - 38

First and second intermediate layers were formed on an aluminum cylinder in the same manner as in Examples 21, 24, 26 or 29.

Separately, a coating liquid for forming a charge generation layer was prepared by adding 4 parts of oxytitanium phthalocyanine pigment to a solution of 2 parts of polyvinyl butyral (BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 34 parts of cyclohexane, subjecting the mixture to dispersion for 8 hours using a sand mill, and diluting the dispersion with 60 parts of tetrahydrofuran. This liquid was applied to the above intermediate layer and dried to form a charge generation layer having a thickness of 0.2 µm.

In the same manner as in Example 11, a charge transport layer was formed.

The obtained electrophotographic photosensitive member was mounted in a reversal development type laser printer, which carried out the steps of charging, exposure, development, image transfer and cleaning in a cycle of 6 seconds, and the durability was tested by continuously printing 5,000 sheets of images under high temperature and high humidity (30 ºC, 85% RH). The evaluation was carried out by measuring the dark area potential (VD) at the initial stage, the light area potential (VL) at the initial stage and after the durability test and by visual inspection of the printed images.

The results are shown in Table 5.

Comparison example 7

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 35 except that the first intermediate layer and the second intermediate layer were formed in the same manner as in Comparative Example 6 by dip coating.

The results are shown in Table 5. Table 1 Table 2 Table 3 Table 4 Table 5

Claims (20)

1. An electrophotographic photosensitive member comprising an electroconductive support, an intermediate layer formed on the electroconductive support, and a photosensitive layer formed on the intermediate layer, wherein the intermediate layer contains a resin having a polycarbamoylcarboxylic acid structure or a polycarbamoylcarboxylic acid ester structure, the resin having a carbamoylcarboxylic acid structure or carbamoylcarboxylic acid ester structure represented by the following formula (2): wherein A2 is a divalent organic group; R9 to R14 are independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a cyano group; R15 and R16 are independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyalkyl group or a substituted or unsubstituted aralkyl group; and X is an oxygen atom, a substituted or unsubstituted alkylene group, a carbonyl group or a sulfonyl group. 2 - Electrophotographic photosensitive member according to Claim 1, wherein A₂ is represented by the formula (3) or (4): -Ar1- (3) wherein Ar₁ is a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group; or -Ar₂-Y-Ar₃- (4) wherein Ar₂ and Ar₃ are independently a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group; and Y is an oxygen atom, a sulfur atom, a substituted or unsubstituted alkylene group, a carbonyl group or a sulfonyl group. 3. An electrophotographic photosensitive member according to Claim 2, wherein A₂ is represented by the formula (4). 4. An electrophotographic photosensitive member according to claim 1, wherein the intermediate layer contains an electrically conductive substance. 5. An electrophotographic photosensitive member according to claim 4, wherein the intermediate layer consists of a first layer containing an electrically conductive substance and a second layer not containing an electrically conductive substance. 6. An electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer consists of a charge generating layer and a charge transporting layer. 7. An electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member consists of an electrically conductive support, an intermediate layer, a charge generating layer and a charge transporting layer arranged in the order mentioned. 8. An electrophotographic photosensitive member according to claim 1, wherein the resin has a segment having the carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure in an amount of 20 to 80 mol% of the segments in the entire resin. 9. An electrophotographic photosensitive member according to claim 8, wherein the resin has a segment having the carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure in an amount of 40 to 60 mol% of the segments in the entire resin. 10. A process cartridge comprising an electrophotographic photosensitive member and at least one device selected from an electrostatic charging device, a developing device and a cleaning device; wherein the electrophotographic photosensitive member is a member according to claim 1, and the electrophotographic photosensitive member and at least one means selected from an electrostatic charging means, a developing means and a cleaning means are integrated into a body which can be dismounted from the main body of an electrophotographic apparatus. 11. An electrophotographic apparatus comprising an electrophotographic photosensitive member, an electrostatic charging device, an image exposing device, a developing device and an image transfer device; wherein the electrophotographic photosensitive member is a member according to claim 1. 12. An electrophotographic photosensitive member comprising an electrically conductive support, an intermediate layer formed on the electrically conductive support, and a photosensitive layer formed on the intermediate layer, wherein the intermediate layer contains a resin having a polycarbamoylcarboxylic acid structure or a polycarbamoylcarboxylic acid ester structure of the formula (1): wherein A1 is a divalent organic group; R1 to R6 are independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group or a cyano group; R7 and R8 are independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxyalkyl group or a substituted or unsubstituted aralkyl group; wherein the intermediate layer is free of a conductive substance. 13. An electrophotographic photosensitive member according to claim 12, wherein A₁ is represented by the formula (3) or (4): -Ar1- (3) wherein Ar₁ is a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group; or -Ar₂-Y-Ar₃- (4) wherein Ar₂ and Ar₃ are independently a substituted or unsubstituted aromatic hydrocarbon group or a substituted or unsubstituted aromatic heterocyclic group; and Y is an oxygen atom, a sulfur atom, a substituted or unsubstituted alkylene group, a carbonyl group or a sulfonyl group. 14. An electrophotographic photosensitive member according to claim 13, wherein A₁ is represented by the formula (4). 15. An electrophotographic photosensitive member according to claim 12, wherein the photosensitive layer consists of a charge generating layer and a charge transporting layer. 16. An electrophotographic photosensitive member according to claim 12, wherein the electrophotographic photosensitive member is composed sequentially of an electrically conductive support, an intermediate layer, a charge generating layer and a charge transporting layer. 17. An electrophotographic photosensitive member according to claim 12, wherein the resin has a segment having the carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure in an amount of 20 to 80 mol% of the segments in the entire resin. 18. An electrophotographic photosensitive member according to claim 17, wherein the resin has a segment having the carbamoylcarboxylic acid structure and the carbamoylcarboxylic acid ester structure in an amount of 40 to 60 mol% of the segments in the entire resin. 19. A process cartridge comprising an electrophotographic photosensitive member and at least one device selected from an electrostatic charging device, a developing device and a cleaning device; wherein the electrophotographic photosensitive member is a member according to claim 12; wherein the electrophotographic photosensitive member and at least one device selected from an electrostatic charging device, a developing device and a cleaning device are arranged in a body that can be removed from the main body of an electrophotographic device. 20. An electrophotographic apparatus comprising an electrophotographic photosensitive member, an electrostatic charging device, an image exposing device, a developing device and an image transfer device; wherein the electrophotographic photosensitive member is a member according to claim 12.